Many a joke has been told about how difficult it has become to find a decent .com address. But yesterday the search for an Internet domain name became a bit easier – if also a bit more pricey.

In addition to .com, .biz and .tv, the suffix .co is now available to those looking to register a new URL. Originally, .co was just the Internet country code for Colombia (just as .tv is the code for Tuvalu). But after research revealed that people associated .co with business and commerce, the South American country decided to capitalize on the fortunate address and sell URLs on the open market. Yesterday was the first day that those URLs went live.

The company that won the right to sell the domains, .CO Internet SAS, said 39,000 applicants have sought .co addresses since they became available for registration in February. The URLs registered include 70 percent of the brands listed in the Brand Finance top 500, including Nike, eBay, Coca-Cola, Apple and Amazon.

But .co Internet SAS is hoping to maintain civility among its domain owners, keeping out cyber squatters and others who might not have a legitimate claim on a particular address. To that end, it has promised to maintain a more transparent registration processes and a “rapid takedown” program.

It is also seeking to maximize profit, charging a premium for coveted addresses that deep-pocketed companies will pay more to own.

The biggest check so far was written by Overstock.com, which paid $350,000 to obtain O.co. Jonathan Johnson, president of Overstock, said the price was justified by the opportunities it affords his company.

“Single-letter domain names are very rare,” he said. “And as we’ve grown from a company that was originally a liquidator to one that sells homes and cars, I could see our brand morphing away from ‘Overstock” and toward the ‘O.’ It enhances our brand.”

.CO Internet SAS has also reserved about 20,000 generic domain names (e.g., Insure.co, Car.co) that it will auction off over the coming year.

“We didn’t want to make them first-come first-served so that the guys with the fastest computers could just snatch them all up,” said Lori Ann Wardi, director of partner relations at .CO Internet SAS. “We also want to be sure that the people getting these domain names will be doing something with them.”